圣诞快乐： 用 GaussDB T 绘制一颗圣诞树，兼论高斯数据库语法兼容

SELECT
CASE WHEN ENMOTECH = 1 THEN lpad('*',
	GAO,
' ')
ELSE lpad(' ',
	GAO + 1-ENMOTECH,
' ') || rpad('*',
	lag(ENMOTECH) OVER (PARTITION BY 1
ORDER BY
	ENMOTECH) + ENMOTECH -2,
'*')
END "圣诞快乐!"
FROM
(SELECT
LEVEL ENMOTECH ,
MAX(LEVEL) OVER (PARTITION BY 1) GAO
FROM dual
CONNECT BY LEVEL < 19 )
UNION ALL
SELECT
lpad(lpad('*',3,'*'),19)
FROM dual
CONNECT BY LEVEL < 5;

Case When；
LAG 分析函数；
CONNECT by；

WITH leaf AS (
SELECT
lpad(rpad('*',
	(ROWNUM-1)* 2 + 1,
'*'),
ROWNUM + 20) leaf,
ROWNUM
FROM
	dual
CONNECT BY
LEVEL <= 3),
lv AS (
SELECT
ROWNUM lv
FROM
	dual
CONNECT BY
LEVEL <= 5),
leafs AS (
SELECT
lpad(rpad('*',
	(ROWNUM-1)* 2 + 1 +(lv-1)* 2,
'*'),
ROWNUM + 20 + lv) leaf
FROM
	leaf,
	lv),
root AS (
SELECT
lpad(rpad('*',
5,
'*'),
24)
FROM
	dual
CONNECT BY
LEVEL <= 4)
SELECT
	leaf
FROM
	leafs
UNION ALL
SELECT
	*
FROM
	root;